Lamp with means to improve lumen maintenance



I June 26, 1945 w ANDERSON 2,379,058

LAMP WITH MEANS TO IMPROVE LUMEN MAINTENANCEL Filed April 6, 1945INVENTOR M E'. fl/VOFE60A ATTORNEY Patented June 26; 1945 UNITED STATESPATENT OFFICE LAMP WITH MEANS TO IMPROVE LUMEN MAINTENANCE Waldemar E.Anderson, Montclair, N. 1., assignor to Westinghouse ElectricCorporation, East Pittsburgh, Pa., a corporation oi PennsylvaniaApplication April 6, 1943, Serial No. 481,958

' 6 Claims. (Cl. 176-16) This invention relates to incandescent electriclamps and, more particularly, to such of the gas-filled type havingmeans to reduce bulb blackening.

The principal object 01' my invention, generally considered, is toprovide an electric lamp,

' and particularly one of the high wattage type,

with an improved blackening collector in order to improve the lumenmaintenance. 1

Another object o! my invention is the employment of metalblackening-collectors, in the envelopes of incandescent electric lamps,which involve an improvement over those previously employed bycomprising a metal'of the pair consistingof chromium and aluminum.

A further object 01 my invention is the provision of a gas-filledlamp,particularly adapted for projection purposes, containing one or morescreens or plates held in such a position with respect to theincandescible filament that they reduce 'bulb blackening as well ascatch some of the blackening, which necessarily occurs, and prevent itfrom depositing onthe inner surface of the glass envelope, therebyimproving lumen maintenance. 1

Other objects and advantages of the invention,

relating to the particular arrangement and construction of the variousparts, will become apparent asthe description proceeds.

Referring to the drawing illustrating my invention:

Fig. l is a side elevational view of an incandescent electric lamp oithe medium bi-post type embodying my invention.

Fig. 2 is a side elevational view of a projection lamp and involvinganother embodiment of my invention.

In the Anderson patent, No. 2,183,952, granted December 19, 1939, thereis disclosed a high powered gas-filled lamp of the medium bi-post typecontaining a collector screen which may be iormed of metal and isdesigned to collect the material which vaporizes from the tungstenfilament and thereby, to that extent, reduce bulb blackening andimproved lumen maintenance.

In the Nutto patent, No. 2,181,522, granted March 21, 1939, there isdescribed and claimed an incandescent electric lamp of the high poweredor projection type, in the envelope oi. which are mounted imperforateplates formed of metal, such as nickel or molybdenum, for the purpose ofI have experimented in order to determine if lumen maintenance can befurther improved by changing the character of the collector. My firsttest consisted in coating a nickel wire mesh with powdered aluminumapplied as a paste. This test showed an advantage in lumen maintenanceat 70% designed life for the coated screen in 500 watt, 120 volt, T20,medium bi-post general lightin lamps.

In another test I used a chromium-plated nickel wire screen which showeda still better lumen maintenance at 70% designed life.

Now referring to the drawing in detail, and first considering theembodiment of my invention illustrated in Fig. 1, there is shown a highwattage lamp ll, of the medium bi-post type,

7 comprising an envelope I2 provided with a base I3 through which extendlead-in conductors I4 and I5 from terminal posts I8 and H. Theleaddecreasing the amount of metal evaporated from the filament duringoperation, as well as collecting the metal which does evaporate, to asgreat an extent as possible.

to receive the conductors or support leads I8 and I9, the lower ends ofwhich may be secured to said conductors I4 and I5 in any desired manner,as by crimping indicated at 2| and 22.

The free or upper ends of the conductors I8 and I8 are, in the presentembodiment, connected by wires 23 and 24,- the outer ends of which arespot welded thereto, and the inner ends embedded in a glass or otherinsulating portion 25. Intermediate portions 'of the conductors l8 andI9 are likewise connected by wires 26 and 21, the adjacent ends of whichare embedded in a glass or other insulating portion 28.

The filament 23, illustrated as of the coil tungsten variety, is shownmounted between the conductors I8 and I9 and the insulators 25 and 28,the end sections 3| of said filament being fitted over stifiening wires32, the filament and 'wires welded or otherwise secured to theconductors I8 1 and I9, and intermediate portions draped over hooks 33,34 and 35, extending from the insulator 25 and hooks 36 and 31 extendingfrom the screen 42 shown in Fig. 11 of the Anderson patent, abovereferred to.

In accordance with my invention, this screen desirably consists of wireof -metal which has a relatively high melting point so as not to failduring operation of the lamp, metals of such a character being nickel,molybdenum and iron, said wire being coated or plated with chromium oraluminum. The chromium is desirably applied as plating, and aluminum, ifused, is desirably pure as in the form of degreased aluminum flakes andapplied with a harmless binder such as alcohol or amyl acetate.

The reference character 4| represents a screen generally similar to thescreen 4|, but inverted, and supported from the insulator 28, in amanner similar to the support of the screen 4|, as by means of spuds 38and 38'.

When the envelope I2 has been filled with an inert gas and sealed, thelamp as just described is one of the high wattage type suitable forprojection or general lighting purposes. On account of carrying thenecessary high current, failure of the filament is apt to result in adestructive arc between the adjacent ends of the said filament. In orderto avoid such an are I provide, in the present embodiment, a fuse 42which may correspond with that described in connection with the firstembodiment of said Anderson patent.

Referring now to the embodiment of my invention illustrated in Fig. 2,there is shown a lamp I l comprising a bulb l2 with a base indicated at43 and enclosing a mount 44. The mount of the present embodimentcomprises a flare tube 45 sealed to the bulb and having an exhaust tube(not shown), an arbor 46 extending from the press 41, lead-in conductorsextending through the press from the base 43 and connected withrelatively rigid inner supporting leads 48 and 49 which may be formed ofnickel or other suitable material, with their normally lower endsembedded in the press 41.

In the present embodiment, the normally upper or free ends of thesupporting leads 48 and 49 are connected by wires and 52, the outer endsof which are spot welded thereto and the inner ends of which areembedded in an insulating member or bridge 53, which may be a piece ofglass cane.

Depending from the insulator 53 are a plurality of supporting members54, 55, 56, 51 and 5B, the number depending on how many coil sectionsthe filament 59 includes. In the present embodiment the coil filamentcomprises 8 tungsten sections which are connected by intersection loopsand staggered so that four are disposed in one normally vertical planeand four in a normally vertical plane parallel thereto, and so spacedthat in plan they lie at the vertices of isosceles triangles.

The upper uncoiled portions of the connected sections of the filament 59are draped over the hooked ends of the members 54 to 58, inclusive, asillustrated, and the extreme coiled end sections 6| and 62'forced overconnecting members 63 and 64, the outer ends of which are desirably spotwelded to the supporting 1eads 48 and 49, respectively. Outer coils 65and 66 may be screwed over the coiled end portions 6| and 62 forshortcircuiting the turns thereof to improve the uniformity of rating.

In order to hold the filament 3| in position between the leads 48 and49, and at the same time avoid undue strains due to expansion andcontraction of the metal parts of the lamp, I provide a light bridgeassembly 61, which desirably comprises an insulating portion 68,preferably formed of glass cane, and end wires 89 and H, the inner endsof which are embedded in the insulator 68 and the outer ends of whichnormally extend diagonally outward and upward and are formed with eyesor loops l2 and 13 to receive and slide on the supporting leads 48 and49, respectively.

The bridge device 61 is normally suspended from the filament 59 byhaving members 14, i5, 16 and 11, the lower ends of which are embeddedin the insulator 68 and the upper ends of which are bent to hook overthe loops formed between the lower portions of the coil sections of thefilament 59 The insulator 68 is desirably provided with a bottom guide18, slidably cooperating with a wire 19 extending upwardly from thearbor 46, in order to prevent undesired tilting of the bridge devicewhen the lamp is inclined from its normal, vertical base-down, position.

Inasmuch as the lamp illustrated is of a type in which the filament isoperated at a very high temperature to give a great amount of light witha relatively short life, said filament is desirably surrounded by inertgas and metal plate means used to reduce vaporization thereof. In thepresent embodiment, these means comprise a pair of plates 8|, shownimperforate, which plates are of metal such as nickel, molybdenum oriron, which has a sufficiently high fusing point to avoid melting duringnormal lamp operation. The surfaces of said plates are coated withchromium or aluminum, like the surfaces of the Wires of the screendescribed in connection with the first embodiment. In edge elevation theplates 8| may appear as shown in Fig. 2, and in perspective as shown inFig. 1 or Fig. 4, of the Nutto patent previously referred to.

These plates are desirably mounted so as to normally extend above andlie on either side of the filament, as illustration in Fig. 2supplemented by the showin of said Nutto patent. For that purpose saidplates are secured to the ends of a wire 82, as by spot welding, whichwire is looped over the insulating bridge member 53 and supportedtherefrom as by spot welding to a spud 83 extending upwardly fromapproximately the midportion thereof. In order to improve the connectionbetween the wire 82 and the spud 83, the curved upper portion of saidwire desirably has first applied thereto a metallic flux which mayconsistof a coil 84 of relatively fine wire. The plates 8| may otherwisebe constructed and disposed as specifically described in said Nuttopatent, referred to, except for the coating or plating of chromium oraluminum thereover.

From the foregoing it will be seen that I have devised an incandescentelectric lamp in which improved means are provided for reducing theamount of metal vaporized during the operation and also for collectingthe metal 'whichdoes vaporize, thereby preventing to a large extent itsdeposition on the bulb and improving the lumen maintenance throughoutlife.

Although preferred embodiments of my invention have been disclosed, itwill be understoodterial of the group consisting of plated chromium anddegreased aluminum flakes.

2. An incandescent electric lamp comprising a envelope, a stem, interiorsupporting leads extending from said stem in said envelope, a filamentmounted between said leads, and a blackening collector supported in saidenvelope, said collector being formed of nickel plated with metallicchromium.

3. An incandescent electric lamp comprising 10 an envelope, a stem,interior supporting leads extending from said stem in said envelope, afilament mounted between said leads, and a blackening collectorsupported in said envelope, said WALDEMAR E. AnDERsoN.

